Investigation of vibration‐induced artifact in clinical diffusion‐weighted imaging of pediatric subjects

It has been reported that mechanical vibrations of the magnetic resonance imaging scanner could produce spurious signal dropouts in diffusion‐weighted images resulting in artifactual anisotropy in certain regions of the brain with red appearance in the Directionally Encoded Color maps. We performed a review of the frequency of this artifact across pediatric studies, noting differences by scanner manufacturer, acquisition protocol, as well as weight and position of the subject. We also evaluated the ability of automated and quantitative methods to detect this artifact. We found that the artifact may be present in over 50% of data in certain protocols and is not limited to one scanner manufacturer. While a specific scanner had the highest incidence, low body weight and positioning were also associated with appearance of the artifact for both scanner types evaluated, making children potentially more susceptible than adults. Visual inspection remains the best method for artifact identification. Software for automated detection showed very low sensitivity (10%). The artifact may present inconsistently in longitudinal studies. We discuss a published case report that has been widely cited and used as evidence to set policy about diagnostic criteria for determining vegetative state. That report attributed longitudinal changes in anisotropy to white matter plasticity without considering the possibility that the changes were caused by this artifact. Our study underscores the need to check for the presence of this artifact in clinical studies, analyzes circumstances for when it may be more likely to occur, and suggests simple strategies to identify and potentially avoid its effects. Hum Brain Mapp 36:4745–4757, 2015. © 2015 Wiley Periodicals, Inc.     

Altered chromatin landscape in circulating T follicular helper and regulatory cells following grass pollen subcutaneous and sublingual immunotherapy

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Monorail™ Piccolino catheter: A new rapid exchagne/ultralow profile coronary angioplasty system

The Monorail^TM Piccolino coronary angioplasty balloon catheter (MBC) was evaluated on 118 patients at two centers. Technical success was achieved in 110 patients (93%). Time for catheter exchange and total fluoroscopy time were significantly lower for the Monorail catheter than with standard equipment (exchange time 97 vs. 170 seconds P <.05 and fluoroscopy time 17 vs. 88 seconds P < 0.001). The advantages of rapid exchange and the ability of utilize 2 Monorail balloon catheters through one 9F guiding catheter for simultaneous inflations allowed for maximal flexibility in treating patients with bifurcation lesions. The double wire approach utilizing one Monorail balloon catheter with a 7F guiding catheter was also technically successful. The Monorail^TM Piccolino balloon catheter has unique features that allow for greater ease of operator use, rapid catheter exchange, and optimal angiographic visualization. It is felt that this catheter design provides distinct advantages over standard angioplasty equipment.     

Covarying alterations in Aβ deposition,glucose metabolism,and gray matter volume in cognitively normal elderly

β‐Amyloid (Aβ), a feature of Alzheimer's disease (AD) pathology, may precede reduced glucose metabolism and gray matter (GM) volume and cognitive decline in patients with AD. Accumulation of Aβ, however, has been also reported in cognitively intact older people, although it remains unresolved whether and how Aβ deposition, glucose metabolism, and GM volume relate to one another in cognitively normal elderly. Fifty‐two cognitively normal older adults underwent Pittsburgh Compound B–positron emission tomography (PIB‐PET), [¹⁸F]fluorodeoxyglucose‐PET, and structural magnetic resonance imaging to measure whole‐brain amyloid deposition, glucose metabolism, and GM volume, respectively. Covariance patterns of these measures in association with global amyloid burden measured by PIB index were extracted using principal component analysis–based multivariate methods. Higher global amyloid burden was associated with relative increases of amyloid deposition and glucose metabolism and relative decreases of GM volume in brain regions collectively known as the default mode network including the posterior cingulate/precuneus, lateral parietal cortices, and medial frontal cortex. Relative increases of amyloid deposition and glucose metabolism were also noted in the lateral prefrontal cortices, and relative decreases of GM volume were pronounced in hippocampus. The degree of expression of the topographical patterns of the PIB data was further associated with visual memory performance when controlling for age, sex, and education. The present findings suggest that cognitively normal older adults with greater amyloid deposition are relatively hypermetabolic in frontal and parietal brain regions while undergoing GM volume loss in overlapping brain regions. Hum Brain Mapp 35:297–308, 2014. © 2012 Wiley Periodicals, Inc.     

In Vitro Evaluation of ECG‐Synchronized Pulsatile Flow Using the i‐cor Diagonal Pump in Neonatal and Pediatric ECLS Systems

The objective was to assess the i‐cor electrocardiogram‐synchronized diagonal pump in terms of hemodynamic energy properties for off‐label use in neonatal and pediatric extracorporeal life support (ECLS) circuits. The neonatal circuit consisted of an i‐cor pump and console, a Medos Hilite 800 LT oxygenator, an 8Fr arterial cannula, a 10Fr venous cannula, 91 cm of 0.6‐cm ID arterial tubing, and 91 cm of 0.6‐cm ID venous tubing. The pediatric circuit was identical except it included a 12Fr arterial cannula, a 14Fr venous cannula, and a Medos Hilite 2400 LT oxygenator. Neonatal trials were conducted at 36°C with hematocrit 40% using varying flow rates (200–600 mL/min, 200 mL increments) and postarterial cannula pressures (40–100 mm Hg, 20 mm Hg increments) under nonpulsatile mode and pulsatile mode with various pulsatile amplitudes (1000–4000 rpm, 1000 rpm increments). Pediatric trials were conducted at different flow rates (800–1600 mL/min, 400 mL/min increments). Mean pressure and energy equivalent pressure increased with increasing postarterial cannula pressure, flow rate, and pulsatile amplitude. Physiologic‐like pulsatility was achieved between pulsatile amplitudes of 2000–3000 rpm. Pressure drops were greatest across the arterial cannula. Pulsatile flow generated significantly higher total hemodynamic energy (THE) levels than nonpulsatile flow. THE levels at postarterial cannula site increased with increasing postarterial cannula pressure, pulsatile amplitude, and flow rate. No surplus hemodynamic energy (SHE) was generated under nonpulsatile mode. Under pulsatile mode, preoxygenator SHE increased with increasing postarterial cannula pressure and pulsatile amplitude, but decreased with increasing flow rate. The i‐cor system can provide nonpulsatile and pulsatile flow for neonatal and pediatric ECLS. Pulsatile amplitudes of 2000–3000 rpm are recommended for use in neonatal and pediatric patients.